These things are simple, relatively inexpensive, and work really well for those cool-but-not-too-hot mornings and days of fall and winter.
Don't expect the warmest shoe cover out there, and they're not water-resistant, but because of that they're just right for days where you need a little extra warmth but don't want too much coverage, or sweaty feet.
Because they're basically oversized socks, they're not the most durable out there, but I typically get a good season out of each pair before I wear them out--and for the price and comfort, I think that's AOK